The present invention relates to an ozone indicator and an ozone sensor ink.
Ozone, by virtue of its high germicidal and other actions, has been utilized for the sterilization and disinfection of foods and instruments or sterilization, disinfection or deodorization of the atmosphere in confined spaces such as the operation theaters of hospitals. On the other hand, ozone is so toxic and deleterious to human health that there is naturally an allowable limit to its concentration. Meanwhile, in photochemical smog forecasts, the atmospheric oxidant level is a significant factor.
For the monitor of ozone concentration, therefore, a variety of methods have been developed for its detection. The principal ozone (oxidant) detection technology available so far takes advantage of the color change according to the following reaction scheme (1).
(O)
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As specific detection methods utilizing the above principle, the optical method which comprises introducing an ozone-containing gas into a solution of potassium iodide and measuring the degree of resultant color change, which is proportional to the amount of liberated iodine, by means of a calorimeter and the expedient method utilizing a simple sensor tube are known.
However, the above optical method is not only complicated procedure-wise but time-consuming, failing to provide real-time data. Moreover, the equipment for practicing the method is very expensive. Particularly when a multi-point simultaneous determination is necessary, a plurality of devices must be installed so that the cost adds up to an enormous sum.
The method using a sensor tube is more expedient than the optical detection method. However, the method is still costly and it is necessary to aspirate the oxidant manually or automatically at each determination.
Thus, regardless of which of those known methodologies is utilized, there remains to be developed an expedient and sensitive method for detecting ozone.
Developed in the above state of the art, the present invention is directed to the following ozone indicator and ozone sensor ink.
1. An ozone indicator comprising (1) at least one color-change layer comprised of an ozone sensor ink and (2) at least one non-color-change layer both formed on a substrate in such a manner that a part or the whole of at least one-color-change layer can be exposed to an ozone-containing atmosphere when the ozone indicator is put to use.
2. An ozone sensor ink comprising an anthraquinone dye having at least one amino group selected from primary and secondary amino groups.